Tosei Takahashi

Salty Food Intake and Risk of Helicobacter pylori Infection

To clarify the risk factors for Helicobacter pylori infection, which is considered to play an etiologic role in atrophic gastritis, duodenal ulcer and gastric cancer, various parameters including diet and socioeconomic characteristics were compared between H. pylori‐infected and non‐infected men. In a cross‐sectional study of 634 men aged 40 to 49 years selected randomly from five areas with different rates of gastric cancer mortality, 474 of 628 men evaluated were positive for IgG antibody against H. pylori. After logistic regression analysis adjusted for area, the results showed a significant association between frequent intake of pickled vegetables and prevalence of H. pylori antibody (odds ratios against men who consume < 1 day/week were 1.19 for 1–2 days/week, 1.92 for 3–4 days/week, 1.90 for 5–7 days/week; P for trend = 0.02). Daily consumption of miso soup was also associated with an increased risk (odds ratio against non‐daily consumer = 1.60, 95% confidence interval = 1.03–2.49). Occupation, number of siblings, education, smoking and alcohol drinking, and other dietary habits were not significantly associated with the prevalence of infection in this population. Although there are limitations in a cross‐sectional study such as this, consumption of salty foods appears to increase the risk of H. pylori infection, which could be a marker of salty food intake or an intermediate risk factor in the etiologic sequence between salty food intake and gastric cancer.

Nutrient consumption and gastric cancer mortality in five regions of Japan

To explore the causes of the threefold variation in mortality rate from gastric cancer in Japan, we studied the geographic correlations between nutrient consumption and the disease in five Public Health Center districts including the regions with the highest and lowest mortality rates in the country. In the winters of 1989-1991, a three-day weighed food record was collected from 207 men and the wives of 165 of the men sampled from the five districts. The average daily consumption of selected nutrients was computed and correlated with the age-adjusted mortality rates from gastric cancer. Partial rank correlation coefficients adjusted for sex and other nutrients were 0.45, -0.80, -0.20, and -0.07 for sodium, carotene, ascorbic acid, and retinol, respectively. The results suggest that variation in gastric cancer mortality in Japan may be partly accounted for by the regional differences in consumption of sodium, carotene, and possibly ascorbic acid.

Quantitative analysis of S-hydroxyguanine in peripheral blood cells: An application for asbestosis patients

SummaryThe quantitative analysis of 8-hydroxy-2′-deoxyguanosine (oh8dG) in human peripheral blood cells was carried out to find integrated biomarkers for estimating cancer risk. The change of the oh8dG levels over time in two healthy volunteers was measured to evaluate a intraindividual variance and each individual value was confirmed to be almost constant when they maintained usual life style. We applied this measurement to asbestosis patients who had worked in dockyard for 19–42 years. The oh8dG were detected in all samples and ranged from 0.77 to 1.28/105 deoxyguanosine (dG). No significant differences was observed in mean values of oh8dG between patients (1.00±0.17/105dG) and hospital control group without asbestos exposure (1.03±0.20/105dG) No association was found with the status of cigarette smoking. The oh8dG level in peripheral blood cells is therefore not a sensitive biomarker for past asbestos exposure at low levels.

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

Objectives: To determine the extent to which interpopulation (between-population) variance, relative to intrapopulation (within-population) variance, contribute to the total variability in nutrient intakes.Design: Cross-sectional study.Setting: Five Public Health Center districts in Japan.Subjects: Two hundred and seven men and 183 spouses.Interventions: A three-day weighed food record.Main outcome measures: The total variance in the consumption of 17 nutrient variables was partitioned by analysis of variance into its inter- and intrapopulation components separately for men and women.Results: The percentage contribution of the interpopulation to total variance differed according to the nutrient; it was notable (8–17%) for total energy, carbohydrates, phosphorus, and sodium in both men and women, but was negligible (less than 4%) for micronutrients such as retinol, carotene, thiamin, riboflavin, niacin and ascorbic acid. The ratio of intra- to interpopulation variance was estimated for 31 nutrients (17 in men and 14 in women). The point estimates of the ratio were larger than unity in all nutrients, and the lower limit of the 95% confidence intervals exceeded unity for all but 5 nutrients. Of the two sources of intrapopulation variation, intraindividual variance was larger than interindividual variance in most of the nutrient.Conclusions: The relative magnitude of interpopulation variation in dietary data can be used to quantify the range of exposure in ecological studies and to examine the heterogeneity of populations pooled for individual-based analysis.Sponsorship: This study was supported in part by Grants-in-Aid for Cancer Research from the Ministry of Health and Welfare, and for Scientific Research from the Ministry of Education, Science and Culture of Japan.

Effects of human diets of two different Japanese populations on cancer incidence in rat hepatic drug-metabolizing and antioxidant enzyme systems

Hepatic enzyme systems of drug metabolism and antioxidation were investigated in rats fed the complete human diets consumed in the two Japanese prefectures, Akita and Okinawa, where the incidence of cancers was quite different: Okinawa had the lowest and Akita the highest age-adjusted mortality rate. In rats fed the human diet consumed in Okinawa, hepatic glutathione S-transferase activity was higher and lipid peroxide content was lower than in rats fed the diet consumed in Akita. These data might indicate that the number and/or quantity of the dietary components attributed to the detoxification of carcinogens and the scavenging reactive carcinogen species was much higher in the foods consumed in the population having lower cancer mortality rate.